I do a buddy training session for two women (same age), and both women wear heart rate monitors during the session. Both clients have their age, height, weight, gender, and resting heart rate entered in to their HR monitors. At the end of a 30-minute session, Client “A” has burned 475 calories while Client “B” has burned only 320 calories. Client “B” is frustrated because she did the exact same work out as Client “A” and did not burn nearly as many calories. Based on the HR monitor readings, Client “A’s” max HR during the session was higher than Client “B’s.” Does this mean that Client “B” is more fit than Client “A” and that it is going to take more exertion for Client “B” to achieve the same calorie burn as Client “A?” Is Client “B” not working as hard as Client “A,” even though Client “B” feels like she worked as hard as she could during the workout? Could it be possible that both clients are equally fit and one just has a physically bigger heart than the other?
as Susan says, there are many variables that serve as possible explanations.
One can be different body weights. By the calibration of caloric energy expenditure, a person with higher body weight will burn more calories if all else is equal.
Another: even though the ‘standard’ of heart rate training is 220 minus age and so on, the true maximum heart rate can vary quite a bit from person to person and can only be determined in a VO2 test. Heart rate monitors just operate with set formulas that cannot take that into account.
Another can be the manufacturer of the heart rate monitors.
I would leave that kind of competition alone and go by rating of perceived exertion which – by your description – appears to be very similar.
Hope this helps.